The primary objective of the Coordinating Core is to ensure integrated, coherent, and effective scientific operations at the HNRC. To support the HNRC in an efficient and accountable manner, the Coordinating Core is organized into four interacting units. The Administrative Unit is responsible for deploying center resources, coordinating Center activities, organizing the annual evaluations of the Center and each Core, coordinating information dissemination to both the scientific and general communities, and ensuring that HNRC research-related activities are fully compliant with all university, state, and federal policies. The Data Management and Information Systems Unit tracks all Center-related data and ensures seamless interaction with external projects via an Internet-accessible data resource system, supports international efforts, and maintains the HNRC web site for internal and external information dissemination. The Statistics Unit consults with investigators and provides statistical services during all phases of project development, implementation, and publication of findings. The Participant Accrual and Retention (PAR) Unit recruits new cohorts of interest (e.g., early infection cases, older HIV+ adults), maintains an informative longitudinal cohort (n = 300), manages a roster of potential targeted study participants, recruiting them as required for specific HNRC-associated studies, and provides technical and consulting services to HNRC-affiliated projects. In addition to the services provided as core resources, the Data Management, Statistics, and PAR Units will also develop new methods to enhance their services. To facilitate its functioning the Core established several working groups. The internal groups include the Council of Investigators (sets policy and reviews scientific progress);the Research Review Committee (reviews requests for Center resources and provides a forum to discuss proposed studies and manuscripts);the Director's Staff (assists in the dayto- day management of the Center) with its Evaluation Committee (regularly reviews HNRC progress indicators for reports to the Director and COI);and the Human Subjects Committee (monitors Human Subjects and IRB issues, especially confidentiality). The external groups include the Scientific Advisory Board (provides periodic independent review of HNRC scientific and programmatic progress), the Participants Advisory Board (provides feedback from participants to the Director), and the Community Advisory Board (provides advice and feedback on the functioning of the Center in various local communities). Through those processes and structures the Coordinating Core assures the operation of a truly multidisciplinary research center and provides central coordination for international research and training efforts.